"I have to go to Pittsburgh," you moan to your friends, dreading the prospect of 48 hours in a city you dimly recall from a forced 1980 family trip: a dreary downtown, surrounded by sleepy hills and dirty rivers. Though you've heard the buzz about the city's selection as host of the G-20 summit this week and its recent rankings as the nation's "most livable" city, you privately assume that if it's livable, it's lame.

Fear not. As locals know, the Burgh's latest incarnation, clean and green, pulls its rivers, hills and past into a handsome present. (How do I know this? Reader, I married it.)

Pity the G-20 horde, trapped inside a downtown "security perimeter" for the summit. True, they'll get a spectacular view of all three rivers (the Allegheny, the Monongahela and the Ohio), the downtown Cultural District (a chic 14-block stretch of theaters and art galleries reclaimed from an icky porn strip) and a spectacular light show projected on nearby buildings. But Pittsburgh claims 89 neighborhoods, and downtown is only one. I recently struck out on foot to explore three neighborhoods in three directions: due north, to an enclave of pop art on the North Shore, southeast to erudite Oakland, and east to Lawrenceville, a Brooklynesque area surrounding a storied cemetery. Escape from downtown and you, too, can walk this way.

As I stroll north across the Andy Warhol Bridge on a perfect early fall afternoon, I pause to watch a flock of kayakers paddle down the Allegheny to the Point, where a fountain marks the famous river confluence like an exclamation point. But I'm en route to visit another Pittsburgh icon.

The Warhol Museum, two blocks past the graceful suspension bridge, celebrates the master of Pop art and self-promotion in a six-story wedding-cake building. (A different kind of family collection -- with his real family name -- lies up the hill, at the Warhola junkyard.) A black-clad crowd will arrive later for a Friday evening ritual that includes cocktails, Warhol movies and live music. I make my way through the ever-changing selection of the Warhol's greatest hits -- silk-screened celebrity portraits, Brillo boxes and even a life-size stuffed Great Dane -- to "Silver Clouds," his cheerful roomful of floating mylar balloons.

While the Warhol is surprisingly kid-friendly (well, maybe not the urine paintings), the nearby Children's Museum is surprisingly artistic. The grand former post office is one of a handful of landmarks that have been carefully refurbished for LEED certification, making some of Pittsburgh's oldest buildings its most energy-efficient. As I walk toward the museum, a giant wind sculpture of movable scales ruffles the entryway in the breeze, in a contemporary installation by Ned Kahn.

Inside, parents and toddlers seem equally transfixed by "Text Rain," which lets visitors use their bodies to catch and bounce cascading letters projected on a video screen.

My final stop is the neighborhood's quirkiest arts venue. Specializing in contemporary installation art, the Mattress Factory fills a foreboding old warehouse with baffling, disturbing and often beautiful statements. The fun comes from watching other visitors' reactions to some seriously weird displays, such as the polka-dotted mannequins in a mirrored room by Yayoi Kusama and ethereal light sculptures by James Turrell. It's a relief to encounter the nearby Monterey Pub, a tiny cafe whose menu and decor are easier to understand.

Back downtown, I hop a Fifth Avenue bus. En route to Oakland, the city's Beaux Arts heart, we crest a hill, and the dark Monongahela River swings into view, its coal barges pushed by sturdy tugboats. Forty years ago, the smoky steel mills along these banks began to cool, bringing the local economy to its knees. Their blast furnaces were replaced by gleaming labs for medical and robotics research. The combination, powered by Carnegie Mellon University and the University of Pittsburgh atop the hill, has fueled the city's new high-tech identity.

Five minutes later the bus disgorges us on Pitt's campus, by one of the Seven Wonders of the World. Well, its stunt double, anyway. The massive Soldiers and Sailors Memorial, crowning a green lawn, is modeled on the ancient mausoleum of Halicarnassus, a clue to the lofty intellectual aspirations of the neighborhood. The Cathedral of Learning, Pitt's tallest building, is a Gothic skyscraper, and the bulging columns of the Mellon Institute at CMU are straight out of Fritz Lang -- Beaux Arts on steroids. The world's greatest thinkers sit in armchairs at the entrances to the Carnegie Museums, created by Andrew Carnegie for the edification of his 19th-century workers. Now the Museum of Natural History and its partner, the Carnegie Museum of Art, deliver a snappy one-two punch of art masterworks and dueling T. rex fossils. Outside, the thinkers can gaze at the students lolling on adjacent Schenley Plaza. The lawn is comfortably edged with gardens, a carousel and outdoor cafes. I follow the sound of a string trio to a concert band shell, where I watch a group of tango dancers trace elegant lines onstage.

When Pittsburgh shops, it starts close to the convention center, in the city's Strip District. This area by the rail yards isn't a red-light enclave but a wholesale food market attracting early-morning shoppers and late-night clubbers. Primanti's serves both, with a he-man menu of meat, french fries and coleslaw wedged into the thick Italian bread. I head down Penn Avenue for fresh kitsch, found in abundance at Mike Feinberg Co. Signs in the black and gold window declare the store the headquarters for Steeler merchandise (and bingo supplies). Inflatable Steelers? Inflatable whoopee cushion? Check and check.

The retail district gets younger as I make the 15-block journey to Lawrenceville. New owners have repainted century-old facades in bright, open-for-business colors: the Practique studio proclaims "yoga is my health insurance," and Dozen Bake Shop offers trendy gourmet cupcakes. I stop in at Sugar, a Butler Street boutique, to see the latest from local fashion designers and pause to check the night's entertainment at the Thunderbird Cafe (indie blues with James McMurtrie) and Arsenal Bowl (the '30s bowling alley woos Gen-X keglers with DJ Zombo and a full bar). Both are options to consider after a dinner at Piccolo Forno, a BYOB with Tuscan flair.

The hipster action fades as I enter Allegheny Cemetery, a bucolic Civil War-era graveyard with fountains, marble monuments and 15 miles of winding lanes. Though it's the resting place of 124,000 Pittsburghers, it's alive with young, stroller-pushing moms, runners and dog walkers. Welcoming the city's youngest residents as well as the remains of its oldest, it's a good place to reflect on how each generation changes a city -- and what Pittsburgh might look like a few decades hence, during its next G-20 summit.